I recently found a new game that is tank vs. tank combat and actually not bad. It requires a download, but is loads of fun to play. It is all PvP and you control a tank from either the Soviet Union (big guns and decent armor, but lacks speed and accuracy), Nazi Germany (Great accuracy, good armor, good speed, okay guns and very expensive gear), or the Americans (Fastest tanks, medium guns, but will get creamed very quickly in a head-to-head brawl). There are also different types of tanks you can unlock, but you start out with light tanks (fast but easy kills). It'll take a while to get off the ground, since your beginner tanks have pathetic guns and no real armor, but once you get into it a bit and upgrade the tanks, even a light tank can hold it's own with the big boys with the right tools.
There is also a wiki you can visit that explains things more then I can here. Hope to see some of you there, the name is Raveneye there.
